Theorycrafting shows that you're right. With same item base and buffs :

- a "Cindercoat" build (as in http://www.d3planner.com/231255107) does 66M effective DPS.
- a "Sparker" build (as in http://www.d3planner.com/679826954) does 57M effective DPS.

And the gear is easier to get. Cindercoats are "not-so-rare" drops when you gamble chest armors at Kadala, and you don't really need an ancient one. Sparkers are very rare and you need an ancient one...